Package io.vavr.collection

Interface Map<K,V>

Type Parameters:

K - Key type

V - Value type

All Superinterfaces:

Foldable<Tuple2<K,V>>, Function<K,V>, Function1<K,V>, Iterable<Tuple2<K,V>>, PartialFunction<K,V>, Serializable, Traversable<Tuple2<K,V>>, Value<Tuple2<K,V>>

All Known Subinterfaces:

SortedMap<K,V>

All Known Implementing Classes:

HashMap, LinkedHashMap, TreeMap

public interface Map<K,V>
extends Traversable<Tuple2<K,V>>, PartialFunction<K,V>, Serializable

An immutable Map interface.

Represents a collection of key-value pairs with immutable operations. Supports typical map operations such as querying, updating, filtering, transforming, and iterating over entries. Provides convenient methods for converting to standard Java maps and for working with default values.

Field Summary

Fields

Modifier and Type	Field	Description
static final long	serialVersionUID	The serial version UID for serialization.

Method Summary

Modifier and Type	Method	Description
default V	apply(K key)	Deprecated.
default PartialFunction<K,V>	asPartialFunction()	Turns this Map into a PartialFunction which is defined at a specific index, if this Map contains the given key.
<K2, V2> Map<K2,V2>	bimap(@NonNull Function<? super K,? extends K2> keyMapper, @NonNull Function<? super V,? extends V2> valueMapper)	Maps this Map to a new Map with different component type by applying a function to its elements.
default <R> Seq<R>	collect(@NonNull PartialFunction<? super Tuple2<K,V>,? extends R> partialFunction)	Applies a PartialFunction to all elements that are defined for it and collects the results.
Tuple2<V,? extends Map<K,V>>	computeIfAbsent(K key, @NonNull Function<? super K,? extends V> mappingFunction)	If the specified key is not already associated with a value, attempts to compute its value using the given mapping function and enters it into this map.
Tuple2<Option<V>,? extends Map<K,V>>	computeIfPresent(K key, @NonNull BiFunction<? super K,? super V,? extends V> remappingFunction)	If the value for the specified key is present, attempts to compute a new mapping given the key and its current mapped value.
default boolean	contains(@NonNull Tuple2<K,V> element)	Shortcut for exists(e -> Objects.equals(e, element)), tests if the given element is contained.
boolean	containsKey(K key)	Returns true if this map contains a mapping for the specified key.
default boolean	containsValue(V value)	Returns true if this map maps one or more keys to the specified value.
Map<K,V>	distinct()	Returns a new Traversable containing the elements of this instance with all duplicates removed.
Map<K,V>	distinctBy(@NonNull Comparator<? super Tuple2<K,V>> comparator)	Returns a new Traversable containing the elements of this instance without duplicates, as determined by the given comparator.
<U> Map<K,V>	distinctBy(@NonNull Function<? super Tuple2<K,V>,? extends U> keyExtractor)	Returns a new Traversable containing the elements of this instance without duplicates, based on keys extracted from elements using keyExtractor.
Map<K,V>	drop(int n)	Returns a new Traversable without the first n elements, or an empty instance if this contains fewer than n elements.
Map<K,V>	dropRight(int n)	Returns a new Traversable without the last n elements, or an empty instance if this contains fewer than n elements.
Map<K,V>	dropUntil(@NonNull Predicate<? super Tuple2<K,V>> predicate)	Returns a new Traversable starting from the first element that satisfies the given predicate, dropping all preceding elements.
Map<K,V>	dropWhile(@NonNull Predicate<? super Tuple2<K,V>> predicate)	Returns a new Traversable starting from the first element that does not satisfy the given predicate, dropping all preceding elements.
static <K, V> Tuple2<K,V>	entry(K key, V value)	Creates a key/value pair for use with Map factories.
Map<K,V>	filter(@NonNull BiPredicate<? super K,? super V> predicate)	Returns a new Map consisting of all elements which satisfy the given predicate.
Map<K,V>	filter(@NonNull Predicate<? super Tuple2<K,V>> predicate)	Returns a new traversable containing only the elements that satisfy the given predicate.
Map<K,V>	filterKeys(@NonNull Predicate<? super K> predicate)	Returns a new Map consisting of all elements with keys which satisfy the given predicate.
Map<K,V>	filterValues(@NonNull Predicate<? super V> predicate)	Returns a new Map consisting of all elements with values which satisfy the given predicate.
<K2, V2> Map<K2,V2>	flatMap(@NonNull BiFunction<? super K,? super V,? extends Iterable<Tuple2<K2,V2>>> mapper)	FlatMaps this Map to a new Map with different component type.
default <U> Seq<U>	flatMap(@NonNull Function<? super Tuple2<K,V>,? extends Iterable<? extends U>> mapper)	Flat-maps this entries to a sequence of values.
default <U> U	foldRight(U zero, @NonNull BiFunction<? super Tuple2<K,V>,? super U,? extends U> f)	Folds the elements of this structure from the right, starting with the given zero value and successively applying the combine function to each element.
default void	forEach(@NonNull BiConsumer<K,V> action)	Performs an action on key, value pair.
Option<V>	get(K key)	Returns the Some of value to which the specified key is mapped, or None if this map contains no mapping for the key.
V	getOrElse(K key, V defaultValue)	Returns the value associated with a key, or a default value if the key is not contained in the map.
<C> Map<C,? extends Map<K,V>>	groupBy(@NonNull Function<? super Tuple2<K,V>,? extends C> classifier)	Groups elements of this Traversable based on a classifier function.
Iterator<? extends Map<K,V>>	grouped(int size)	Splits this Traversable into consecutive blocks of the given size.
default boolean	hasDefiniteSize()	Indicates whether this Traversable has a known finite size.
Map<K,V>	init()	Returns all elements of this Traversable except the last one.
Option<? extends Map<K,V>>	initOption()	Returns all elements of this Traversable except the last one, wrapped in an Option.
default boolean	isDefinedAt(K key)	Deprecated.
default boolean	isDistinct()	Indicates whether this Traversable may contain only distinct elements.
default boolean	isTraversableAgain()	Checks if this Traversable can be traversed multiple times without side effects.
@NonNull Iterator<Tuple2<K,V>>	iterator()	Returns an iterator over the elements of this Traversable, implemented via Traversable.head() and Traversable.tail().
default <U> Iterator<U>	iterator(@NonNull BiFunction<K,V,? extends U> mapper)	Iterates this Map sequentially, mapping the (key, value) pairs to elements.
Set<K>	keySet()	Returns the keys contained in this map.
default Iterator<K>	keysIterator()	Returns the keys contained in this map as an iterator.
default int	length()	Returns the number of elements in this Traversable.
default Function1<K,Option<V>>	lift()	Turns this map into a plain function returning an Option result.
<K2, V2> Map<K2,V2>	map(@NonNull BiFunction<? super K,? super V,Tuple2<K2,V2>> mapper)	Maps the entries of this Map to form a new Map.
default <U> Seq<U>	map(@NonNull Function<? super Tuple2<K,V>,? extends U> mapper)	Maps the Map entries to a sequence of values.
<K2> Map<K2,V>	mapKeys(@NonNull Function<? super K,? extends K2> keyMapper)	Maps the keys of this Map while preserving the corresponding values.
<K2> Map<K2,V>	mapKeys(@NonNull Function<? super K,? extends K2> keyMapper, @NonNull BiFunction<? super V,? super V,? extends V> valueMerge)	Maps the keys of this Map while preserving the corresponding values and applying a value merge function on collisions.
default <U> Seq<U>	mapTo(U value)	Maps the underlying value to another fixed value.
default Seq<Void>	mapToVoid()	Maps the underlying value to Void
<V2> Map<K,V2>	mapValues(@NonNull Function<? super V,? extends V2> valueMapper)	Maps the values of this Map while preserving the corresponding keys.
Map<K,V>	merge(@NonNull Map<? extends K,? extends V> that)	Creates a new map which by merging the entries of this map and that map.
<U extends V> Map<K,V>	merge(@NonNull Map<? extends K,U> that, @NonNull BiFunction<? super V,? super U,? extends V> collisionResolution)	Creates a new map which by merging the entries of this map and that map.
static <K, V> Map<K,V>	narrow(Map<? extends K,? extends V> map)	Narrows a widened Map<? extends K, ? extends V> to Map<K, V> by performing a type-safe cast.
Map<K,V>	orElse(Iterable<? extends Tuple2<K,V>> other)	Returns this Traversable if it is non-empty; otherwise, returns the given alternative.
Map<K,V>	orElse(@NonNull Supplier<? extends Iterable<? extends Tuple2<K,V>>> supplier)	Returns this Traversable if it is non-empty; otherwise, returns the result of evaluating the given supplier.
Tuple2<? extends Map<K,V>,? extends Map<K,V>>	partition(@NonNull Predicate<? super Tuple2<K,V>> predicate)	Splits this Traversable into two partitions according to a predicate.
Map<K,V>	peek(@NonNull Consumer<? super Tuple2<K,V>> action)	Performs the given action on the first element if this is an eager implementation.
Map<K,V>	put(@NonNull Tuple2<? extends K,? extends V> entry)	Convenience method for put(entry._1, entry._2).
<U extends V> Map<K,V>	put(@NonNull Tuple2<? extends K,U> entry, @NonNull BiFunction<? super V,? super U,? extends V> merge)	Convenience method for put(entry._1, entry._2, merge).
<U extends V> Map<K,V>	put(K key, U value, @NonNull BiFunction<? super V,? super U,? extends V> merge)	Associates the specified value with the specified key in this map.
Map<K,V>	put(K key, V value)	Associates the specified value with the specified key in this map.
Map<K,V>	reject(@NonNull BiPredicate<? super K,? super V> predicate)	Returns a new Map consisting of all elements which do not satisfy the given predicate.
Map<K,V>	reject(@NonNull Predicate<? super Tuple2<K,V>> predicate)	Returns a new traversable containing only the elements that do not satisfy the given predicate.
Map<K,V>	rejectKeys(@NonNull Predicate<? super K> predicate)	Returns a new Map consisting of all elements with keys which do not satisfy the given predicate.
Map<K,V>	rejectValues(@NonNull Predicate<? super V> predicate)	Returns a new Map consisting of all elements with values which do not satisfy the given predicate.
Map<K,V>	remove(K key)	Removes the mapping for a key from this map if it is present.
Map<K,V>	removeAll(@NonNull Iterable<? extends K> keys)	Removes the mapping for a key from this map if it is present.
Map<K,V>	removeAll(@NonNull BiPredicate<? super K,? super V> predicate)	Deprecated. Please use reject(BiPredicate)
Map<K,V>	removeKeys(@NonNull Predicate<? super K> predicate)	Deprecated. Please use rejectKeys(Predicate)
Map<K,V>	removeValues(@NonNull Predicate<? super V> predicate)	Deprecated. Please use rejectValues(Predicate)
Map<K,V>	replace(@NonNull Tuple2<K,V> currentElement, @NonNull Tuple2<K,V> newElement)	Replaces the first occurrence of currentElement with newElement, if it exists.
Map<K,V>	replace(K key, V oldValue, V newValue)	Replaces the entry for the specified key only if currently mapped to the specified value.
Map<K,V>	replaceAll(@NonNull Tuple2<K,V> currentElement, Tuple2<K,V> newElement)	Replaces all occurrences of currentElement with newElement.
Map<K,V>	replaceAll(@NonNull BiFunction<? super K,? super V,? extends V> function)	Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception.
Map<K,V>	replaceValue(K key, V value)	Replaces the entry for the specified key only if it is currently mapped to some value.
Map<K,V>	retainAll(@NonNull Iterable<? extends Tuple2<K,V>> elements)	Retains only the elements from this Traversable that are contained in the given elements.
Map<K,V>	scan(@NonNull Tuple2<K,V> zero, @NonNull BiFunction<? super Tuple2<K,V>,? super Tuple2<K,V>,? extends Tuple2<K,V>> operation)	Computes a prefix scan of the elements of this Traversable.
default <U> Seq<U>	scanLeft(U zero, @NonNull BiFunction<? super U,? super Tuple2<K,V>,? extends U> operation)	Produces a collection containing cumulative results of applying the operator from left to right.
default <U> Seq<U>	scanRight(U zero, @NonNull BiFunction<? super Tuple2<K,V>,? super U,? extends U> operation)	Produces a collection containing cumulative results of applying the operator from right to left.
int	size()	Returns the number of elements in this Traversable.
Iterator<? extends Map<K,V>>	slideBy(@NonNull Function<? super Tuple2<K,V>,?> classifier)	Partitions this Traversable into consecutive non-overlapping windows according to a classification function.
Iterator<? extends Map<K,V>>	sliding(int size)	Slides a window of a given size over this Traversable with a step size of 1.
Iterator<? extends Map<K,V>>	sliding(int size, int step)	Slides a window of a specific size with a given step over this Traversable.
Tuple2<? extends Map<K,V>,? extends Map<K,V>>	span(@NonNull Predicate<? super Tuple2<K,V>> predicate)	Splits this Traversable into a prefix and remainder according to the given predicate.
Map<K,V>	tail()	Returns a new Traversable without its first element.
Option<? extends Map<K,V>>	tailOption()	Returns a new Traversable without its first element as an Option.
Map<K,V>	take(int n)	Returns the first n elements of this Traversable, or all elements if n exceeds the length.
Map<K,V>	takeRight(int n)	Returns the last n elements of this Traversable, or all elements if n exceeds the length.
Map<K,V>	takeUntil(@NonNull Predicate<? super Tuple2<K,V>> predicate)	Takes elements from this Traversable until the given predicate holds for an element.
Map<K,V>	takeWhile(@NonNull Predicate<? super Tuple2<K,V>> predicate)	Takes elements from this Traversable while the given predicate holds.
Map<K,V>	toJavaMap()	Converts this Vavr Map to a java.util.Map while preserving characteristics like insertion order (LinkedHashMap) and sort order (SortedMap).
default <U> U	transform(@NonNull Function<? super Map<K,V>,? extends U> f)	Transforms this Map.
default Tuple2<Seq<K>,Seq<V>>	unzip()	Unzips the entries of this Map by treating each key-value pair as an element, and splitting them into two separate Seq collections - one for keys and one for values.
default <T1, T2> Tuple2<Seq<T1>,Seq<T2>>	unzip(@NonNull BiFunction<? super K,? super V,Tuple2<? extends T1,? extends T2>> unzipper)	Unzips the entries of this Map by mapping each key-value pair to a tuple.
default <T1, T2> Tuple2<Seq<T1>,Seq<T2>>	unzip(@NonNull Function<? super Tuple2<K,V>,Tuple2<? extends T1,? extends T2>> unzipper)	Unzips the elements of this Traversable by mapping each element to a pair and splitting them into two separate Traversable collections.
default <T1, T2, T3> Tuple3<Seq<T1>,Seq<T2>,Seq<T3>>	unzip3(@NonNull BiFunction<? super K,? super V,Tuple3<? extends T1,? extends T2,? extends T3>> unzipper)	Unzips the entries of this Map by mapping each key-value pair to a triple.
default <T1, T2, T3> Tuple3<Seq<T1>,Seq<T2>,Seq<T3>>	unzip3(@NonNull Function<? super Tuple2<K,V>,Tuple3<? extends T1,? extends T2,? extends T3>> unzipper)	Unzips the elements of this Traversable by mapping each element to a triple and splitting them into three separate Traversable collections.
Seq<V>	values()	Returns a new Seq that contains the values of this Map.
default Iterator<V>	valuesIterator()	Returns the values in this map.
default Function1<K,V>	withDefault(@NonNull Function<? super K,? extends V> defaultFunction)	Deprecated. Will be removed
default Function1<K,V>	withDefaultValue(V defaultValue)	Deprecated. Will be removed
default <U> Seq<Tuple2<Tuple2<K,V>,U>>	zip(@NonNull Iterable<? extends U> that)	Returns a Traversable formed by pairing elements of this Traversable with elements of another Iterable.
default <U> Seq<Tuple2<Tuple2<K,V>,U>>	zipAll(@NonNull Iterable<? extends U> that, Tuple2<K,V> thisElem, U thatElem)	Returns a Traversable formed by pairing elements of this Traversable with elements of another Iterable, filling in placeholder elements when one collection is shorter than the other.
default <U, R> Seq<R>	zipWith(@NonNull Iterable<? extends U> that, BiFunction<? super Tuple2<K,V>,? super U,? extends R> mapper)	Returns a Traversable by combining elements of this Traversable with elements of another Iterable using a mapping function.
default Seq<Tuple2<Tuple2<K,V>,Integer>>	zipWithIndex()	Zips this Traversable with its indices, starting at 0.
default <U> Seq<U>	zipWithIndex(@NonNull BiFunction<? super Tuple2<K,V>,? super Integer,? extends U> mapper)	Zips this Traversable with its indices and maps the resulting pairs using the provided mapper.

Methods inherited from interface io.vavr.collection.Foldable

fold, reduce, reduceOption

Methods inherited from interface io.vavr.Function1

andThen, arity, compose, compose1, curried, isMemoized, memoized, partial, reversed, tupled

Methods inherited from interface io.vavr.collection.Traversable

arrangeBy, average, containsAll, count, equals, existsUnique, find, findLast, foldLeft, forEachWithIndex, get, hashCode, head, headOption, isEmpty, isOrdered, isSequential, isSingleValued, last, lastOption, max, maxBy, maxBy, min, minBy, minBy, mkCharSeq, mkCharSeq, mkCharSeq, mkString, mkString, mkString, nonEmpty, product, reduceLeft, reduceLeftOption, reduceRight, reduceRightOption, single, singleOption, spliterator, sum

Methods inherited from interface io.vavr.Value

collect, collect, corresponds, eq, exists, forAll, forEach, getOrElse, getOrElse, getOrElseThrow, getOrElseTry, getOrNull, isAsync, isLazy, out, out, stderr, stdout, stringPrefix, toArray, toCharSeq, toCompletableFuture, toEither, toEither, toInvalid, toInvalid, toJavaArray, toJavaArray, toJavaArray, toJavaCollection, toJavaList, toJavaList, toJavaMap, toJavaMap, toJavaMap, toJavaOptional, toJavaParallelStream, toJavaSet, toJavaSet, toJavaStream, toLeft, toLeft, toLinkedMap, toLinkedMap, toLinkedSet, toList, toMap, toMap, toOption, toPriorityQueue, toPriorityQueue, toQueue, toRight, toRight, toSet, toSortedMap, toSortedMap, toSortedMap, toSortedMap, toSortedSet, toSortedSet, toStream, toString, toTree, toTree, toTry, toTry, toValid, toValid, toValidation, toValidation, toVector

Field Details

serialVersionUID

static final long serialVersionUID

The serial version UID for serialization.

See Also:

• Constant Field Values

Method Details

narrow

static <K,
V> Map<K,V> narrow(Map<? extends K,? extends V> map)

Narrows a widened Map<? extends K, ? extends V> to Map<K, V> by performing a type-safe cast. This is eligible because immutable/read-only collections are covariant.

Type Parameters:

K - Key type

V - Value type

Parameters:

map - A Map.

Returns:

the given map instance as narrowed type Map<K, V>.

entry

static <K,
V> Tuple2<K,V> entry(K key,
 V value)

Creates a key/value pair for use with Map factories.

When imported statically, this method enables constructing maps in a readable and type-safe way, for example:

 HashMap.ofEntries(
     entry(k1, v1),
     entry(k2, v2),
     entry(k3, v3)
 );
 

Type Parameters:

K - key type

V - value type

Parameters:

key - the entry's key

value - the entry's value

Returns:

a key/value pair

apply

@Deprecated
default V apply(K key)

Deprecated.

Description copied from interface: PartialFunction

Applies this function to the given argument and returns the result.

Specified by:

apply in interface Function<K,V>

Specified by:

apply in interface Function1<K,V>

Specified by:

apply in interface PartialFunction<K,V>

Parameters:

key - the input argument

Returns:

the result of applying this function to the input

asPartialFunction

default PartialFunction<K,V> asPartialFunction()
                                        throws NoSuchElementException

Turns this Map into a PartialFunction which is defined at a specific index, if this Map contains the given key. When applied to a defined key, the partial function will return the value of this Map that is associated with the key.

Returns:

a new PartialFunction

Throws:

NoSuchElementException - when a non-existing key is applied to the partial function

collect

default <R> Seq<R> collect(@NonNull PartialFunction<? super Tuple2<K,V>,? extends R> partialFunction)

Description copied from interface: Traversable

Applies a PartialFunction to all elements that are defined for it and collects the results.

For each element in iteration order, the function is first tested:

 partialFunction.isDefinedAt(element)
 

If true, the element is mapped to type R:

 R newElement = partialFunction.apply(element)
 

Note: If this Traversable is ordered (i.e., extends Ordered), the caller must ensure that the resulting elements are comparable (i.e., implement Comparable).

Specified by:

collect in interface Traversable<K>

Type Parameters:

R - the type of elements in the resulting Traversable

Parameters:

partialFunction - a function that may not be defined for all elements of this traversable

Returns:

a new Traversable containing the results of applying the partial function

bimap

<K2,
V2> Map<K2,V2> bimap(@NonNull Function<? super K,? extends K2> keyMapper,
 @NonNull Function<? super V,? extends V2> valueMapper)

Maps this Map to a new Map with different component type by applying a function to its elements.

Type Parameters:

K2 - key's component type of the map result

V2 - value's component type of the map result

Parameters:

keyMapper - a Function that maps the keys of type K to keys of type K2

valueMapper - a Function that the values of type V to values of type V2

Returns:

a new Map

Throws:

NullPointerException - if keyMapper or valueMapper is null

contains

default boolean contains(@NonNull Tuple2<K,V> element)

Description copied from interface: Value

Shortcut for exists(e -> Objects.equals(e, element)), tests if the given element is contained.

Specified by:

contains in interface Value<K>

Parameters:

element - An Object of type A, may be null.

Returns:

true, if element is contained, false otherwise.

computeIfAbsent

Tuple2<V,? extends Map<K,V>> computeIfAbsent(K key,
 @NonNull Function<? super K,? extends V> mappingFunction)

If the specified key is not already associated with a value, attempts to compute its value using the given mapping function and enters it into this map.

Parameters:

key - key whose presence in this map is to be tested

mappingFunction - mapping function

Returns:

the Tuple2 of current or modified map and existing or computed value associated with the specified key

computeIfPresent

Tuple2<Option<V>,? extends Map<K,V>> computeIfPresent(K key,
 @NonNull BiFunction<? super K,? super V,? extends V> remappingFunction)

If the value for the specified key is present, attempts to compute a new mapping given the key and its current mapped value.

Parameters:

key - key whose presence in this map is to be tested

remappingFunction - remapping function

Returns:

the Tuple2 of current or modified map and the Some of the value associated with the specified key, or None if none

containsKey

boolean containsKey(K key)

Returns true if this map contains a mapping for the specified key.

Parameters:

key - key whose presence in this map is to be tested

Returns:

true if this map contains a mapping for the specified key

containsValue

default boolean containsValue(V value)

Returns true if this map maps one or more keys to the specified value. This operation will require time linear in the map size.

Parameters:

value - value whose presence in this map is to be tested

Returns:

true if this map maps one or more keys to the specified value

filter

Map<K,V> filter(@NonNull BiPredicate<? super K,? super V> predicate)

Returns a new Map consisting of all elements which satisfy the given predicate.

Parameters:

predicate - the predicate used to test elements

Returns:

a new Map

Throws:

NullPointerException - if predicate is null

reject

Map<K,V> reject(@NonNull BiPredicate<? super K,? super V> predicate)

Returns a new Map consisting of all elements which do not satisfy the given predicate.

Parameters:

predicate - the predicate used to test elements

Returns:

a new Map

Throws:

NullPointerException - if predicate is null

filterKeys

Map<K,V> filterKeys(@NonNull Predicate<? super K> predicate)

Returns a new Map consisting of all elements with keys which satisfy the given predicate.

Parameters:

predicate - the predicate used to test keys of elements

Returns:

a new Map

Throws:

NullPointerException - if predicate is null

rejectKeys

Map<K,V> rejectKeys(@NonNull Predicate<? super K> predicate)

Returns a new Map consisting of all elements with keys which do not satisfy the given predicate.

Parameters:

predicate - the predicate used to test keys of elements

Returns:

a new Map

Throws:

NullPointerException - if predicate is null

filterValues

Map<K,V> filterValues(@NonNull Predicate<? super V> predicate)

Returns a new Map consisting of all elements with values which satisfy the given predicate.

Parameters:

predicate - the predicate used to test values of elements

Returns:

a new Map

Throws:

NullPointerException - if predicate is null

rejectValues

Map<K,V> rejectValues(@NonNull Predicate<? super V> predicate)

Returns a new Map consisting of all elements with values which do not satisfy the given predicate.

Parameters:

predicate - the predicate used to test values of elements

Returns:

a new Map

Throws:

NullPointerException - if predicate is null

flatMap

<K2,
V2> Map<K2,V2> flatMap(@NonNull BiFunction<? super K,? super V,? extends Iterable<Tuple2<K2,V2>>> mapper)

FlatMaps this Map to a new Map with different component type.

Type Parameters:

K2 - key's component type of the mapped Map

V2 - value's component type of the mapped Map

Parameters:

mapper - A mapper

Returns:

A new Map.

Throws:

NullPointerException - if mapper is null

flatMap

default <U> Seq<U> flatMap(@NonNull Function<? super Tuple2<K,V>,? extends Iterable<? extends U>> mapper)

Flat-maps this entries to a sequence of values.

Please use flatMap(BiFunction) if the result should be a Map

Specified by:

flatMap in interface Traversable<K>

Type Parameters:

U - Component type

Parameters:

mapper - A mapper

Returns:

A sequence of flat-mapped values.

foldRight

default <U> U foldRight(U zero,
 @NonNull BiFunction<? super Tuple2<K,V>,? super U,? extends U> f)

Description copied from interface: Foldable

Folds the elements of this structure from the right, starting with the given zero value and successively applying the combine function to each element.

Folding from the right means that elements are combined starting from the last element and associating each step with the accumulated result so far.

Example:

 // Result: "!cba"
 List.of("a", "b", "c").foldRight("!", (x, acc) -> acc + x);
 

Specified by:

foldRight in interface Foldable<K>

Specified by:

foldRight in interface Traversable<K>

Type Parameters:

U - the type of the accumulated result

Parameters:

zero - the initial value to start folding with

f - a function that combines the next element and the accumulated value

Returns:

the folded result

forEach

default void forEach(@NonNull BiConsumer<K,V> action)

Performs an action on key, value pair.

Parameters:

action - A BiConsumer

Throws:

NullPointerException - if action is null

get

Option<V> get(K key)

Returns the Some of value to which the specified key is mapped, or None if this map contains no mapping for the key.

Parameters:

key - the key whose associated value is to be returned

Returns:

the Some of value to which the specified key is mapped, or None if this map contains no mapping for the key

getOrElse

V getOrElse(K key,
 V defaultValue)

Returns the value associated with a key, or a default value if the key is not contained in the map.

Parameters:

key - the key

defaultValue - a default value

Returns:

the value associated with key if it exists, otherwise the default value.

hasDefiniteSize

default boolean hasDefiniteSize()

Description copied from interface: Traversable

Indicates whether this Traversable has a known finite size.

This should typically be implemented by concrete classes, not interfaces.

Specified by:

hasDefiniteSize in interface Traversable<K>

Returns:

true if the number of elements is finite and known, false otherwise.

isTraversableAgain

default boolean isTraversableAgain()

Description copied from interface: Traversable

Checks if this Traversable can be traversed multiple times without side effects.

Implementations should provide the correct behavior; this is not meant for interfaces alone.

Specified by:

isTraversableAgain in interface Traversable<K>

Returns:

true if this Traversable is guaranteed to be repeatably traversable, false otherwise

iterator

@NonNull Iterator<Tuple2<K,V>> iterator()

Description copied from interface: Traversable

Returns an iterator over the elements of this Traversable, implemented via Traversable.head() and Traversable.tail(). Subclasses may override for a more efficient implementation.

Specified by:

iterator in interface Iterable<K>

Specified by:

iterator in interface Traversable<K>

Specified by:

iterator in interface Value<K>

Returns:

a new Iterator over the elements of this Traversable

iterator

default <U> Iterator<U> iterator(@NonNull BiFunction<K,V,? extends U> mapper)

Iterates this Map sequentially, mapping the (key, value) pairs to elements.

Type Parameters:

U - The type of the resulting elements

Parameters:

mapper - A function that maps (key, value) pairs to elements of type U

Returns:

An iterator through the mapped elements.

keySet

Set<K> keySet()

Returns the keys contained in this map.

Returns:

Set of the keys contained in this map.

keysIterator

default Iterator<K> keysIterator()

Returns the keys contained in this map as an iterator.

Returns:

Iterator of the keys contained in this map.

length

default int length()

Description copied from interface: Traversable

Returns the number of elements in this Traversable.

Equivalent to Traversable.size().

Specified by:

length in interface Traversable<K>

Returns:

the number of elements

lift

default Function1<K,Option<V>> lift()

Turns this map into a plain function returning an Option result.

Specified by:

lift in interface PartialFunction<K,V>

Returns:

a function that takes a key k and returns its value in a Some if found, otherwise a None.

map

default <U> Seq<U> map(@NonNull Function<? super Tuple2<K,V>,? extends U> mapper)

Maps the Map entries to a sequence of values.

Please use map(BiFunction) if the result has to be of type Map.

Specified by:

map in interface Traversable<K>

Specified by:

map in interface Value<K>

Type Parameters:

U - Component type

Parameters:

mapper - A mapper

Returns:

A sequence of mapped values.

mapTo

default <U> Seq<U> mapTo(U value)

Description copied from interface: Value

Maps the underlying value to another fixed value.

Specified by:

mapTo in interface Traversable<K>

Specified by:

mapTo in interface Value<K>

Type Parameters:

U - The new component type

Parameters:

value - value to replace the contents with

Returns:

A new value

mapToVoid

default Seq<Void> mapToVoid()

Description copied from interface: Value

Maps the underlying value to Void

Specified by:

mapToVoid in interface Traversable<K>

Specified by:

mapToVoid in interface Value<K>

Returns:

A new value of type Void

map

<K2,
V2> Map<K2,V2> map(@NonNull BiFunction<? super K,? super V,Tuple2<K2,V2>> mapper)

Maps the entries of this Map to form a new Map.

Type Parameters:

K2 - key's component type of the map result

V2 - value's component type of the map result

Parameters:

mapper - a Function that maps entries of type (K, V) to entries of type (K2, V2)

Returns:

a new Map

Throws:

NullPointerException - if mapper is null

mapKeys

<K2> Map<K2,V> mapKeys(@NonNull Function<? super K,? extends K2> keyMapper)

Maps the keys of this Map while preserving the corresponding values.

The size of the result map may be smaller if keyMapper maps two or more distinct keys to the same new key. In this case the value at the latest of the original keys is retained. Order of keys is predictable in TreeMap (by comparator) and LinkedHashMap (insertion-order) and not predictable in HashMap.

Type Parameters:

K2 - the new key type

Parameters:

keyMapper - a Function that maps keys of type V to keys of type V2

Returns:

a new Map

Throws:

NullPointerException - if keyMapper is null

mapKeys

<K2> Map<K2,V> mapKeys(@NonNull Function<? super K,? extends K2> keyMapper,
 @NonNull BiFunction<? super V,? super V,? extends V> valueMerge)

Maps the keys of this Map while preserving the corresponding values and applying a value merge function on collisions.

The size of the result map may be smaller if keyMapper maps two or more distinct keys to the same new key. In this case the associated values will be combined using valueMerge.

Type Parameters:

K2 - the new key type

Parameters:

keyMapper - a Function that maps keys of type V to keys of type V2

valueMerge - a BiFunction that merges values

Returns:

a new Map

Throws:

NullPointerException - if keyMapper is null

mapValues

<V2> Map<K,V2> mapValues(@NonNull Function<? super V,? extends V2> valueMapper)

Maps the values of this Map while preserving the corresponding keys.

Type Parameters:

V2 - the new value type

Parameters:

valueMapper - a Function that maps values of type V to values of type V2

Returns:

a new Map

Throws:

NullPointerException - if valueMapper is null

merge

Map<K,V> merge(@NonNull Map<? extends K,? extends V> that)

Creates a new map which by merging the entries of this map and that map.

If collisions occur, the value of this map is taken.

Parameters:

that - the other map

Returns:

A merged map

Throws:

NullPointerException - if that map is null

merge

<U extends V> Map<K,V> merge(@NonNull Map<? extends K,U> that,
 @NonNull BiFunction<? super V,? super U,? extends V> collisionResolution)

Creates a new map which by merging the entries of this map and that map.

Uses the specified collision resolution function if two keys are the same. The collision resolution function will always take the first argument from this map and the second from that map.

Type Parameters:

U - value type of that Map

Parameters:

that - the other map

collisionResolution - the collision resolution function

Returns:

A merged map

Throws:

NullPointerException - if that map or the given collision resolution function is null

put

Map<K,V> put(K key,
 V value)

Associates the specified value with the specified key in this map. If the map previously contained a mapping for the key, the old value is replaced by the specified value.

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

Returns:

A new Map containing these elements and that entry.

put

Map<K,V> put(@NonNull Tuple2<? extends K,? extends V> entry)

Convenience method for put(entry._1, entry._2).

Parameters:

entry - A Tuple2 containing the key and value

Returns:

A new Map containing these elements and that entry.

put

<U extends V> Map<K,V> put(K key,
 U value,
 @NonNull BiFunction<? super V,? super U,? extends V> merge)

Associates the specified value with the specified key in this map. If the map previously contained a mapping for the key, the merge function is used to combine the previous value to the value to be inserted, and the result of that call is inserted in the map.

Type Parameters:

U - the value type

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

merge - function taking the old and new values and merging them.

Returns:

A new Map containing these elements and that entry.

put

<U extends V> Map<K,V> put(@NonNull Tuple2<? extends K,U> entry,
 @NonNull BiFunction<? super V,? super U,? extends V> merge)

Convenience method for put(entry._1, entry._2, merge).

Type Parameters:

U - the value type

Parameters:

entry - A Tuple2 containing the key and value

merge - function taking the old and new values and merging them.

Returns:

A new Map containing these elements and that entry.

remove

Map<K,V> remove(K key)

Removes the mapping for a key from this map if it is present.

Parameters:

key - key whose mapping is to be removed from the map

Returns:

A new Map containing these elements without the entry specified by that key.

removeAll

@Deprecated
Map<K,V> removeAll(@NonNull BiPredicate<? super K,? super V> predicate)

Deprecated.

Please use reject(BiPredicate)

Returns a new Map consisting of all elements which do not satisfy the given predicate.

Parameters:

predicate - the predicate used to test elements

Returns:

a new Map

Throws:

NullPointerException - if predicate is null

removeAll

Map<K,V> removeAll(@NonNull Iterable<? extends K> keys)

Removes the mapping for a key from this map if it is present.

Parameters:

keys - keys are to be removed from the map

Returns:

A new Map containing these elements without the entries specified by that keys.

removeKeys

@Deprecated
Map<K,V> removeKeys(@NonNull Predicate<? super K> predicate)

Deprecated.

Please use rejectKeys(Predicate)

Returns a new Map consisting of all elements with keys which do not satisfy the given predicate.

Parameters:

predicate - the predicate used to test keys of elements

Returns:

a new Map

Throws:

NullPointerException - if predicate is null

removeValues

@Deprecated
Map<K,V> removeValues(@NonNull Predicate<? super V> predicate)

Deprecated.

Please use rejectValues(Predicate)

Returns a new Map consisting of all elements with values which do not satisfy the given predicate.

Parameters:

predicate - the predicate used to test values of elements

Returns:

a new Map

Throws:

NullPointerException - if predicate is null

scanLeft

default <U> Seq<U> scanLeft(U zero,
 @NonNull BiFunction<? super U,? super Tuple2<K,V>,? extends U> operation)

Description copied from interface: Traversable

Produces a collection containing cumulative results of applying the operator from left to right.

Will not terminate for infinite collections. The results may vary across runs unless the collection is ordered.

Specified by:

scanLeft in interface Traversable<K>

Type Parameters:

U - the type of the resulting elements

Parameters:

zero - the initial value

operation - a binary operator applied to the intermediate result and each element

Returns:

a new Traversable containing the cumulative results

scanRight

default <U> Seq<U> scanRight(U zero,
 @NonNull BiFunction<? super Tuple2<K,V>,? super U,? extends U> operation)

Description copied from interface: Traversable

Produces a collection containing cumulative results of applying the operator from right to left.

The head of the resulting collection is the last cumulative result. Will not terminate for infinite collections. Results may vary across runs unless the collection is ordered.

Specified by:

scanRight in interface Traversable<K>

Type Parameters:

U - the type of the resulting elements

Parameters:

zero - the initial value

operation - a binary operator applied to each element and the intermediate result

Returns:

a new Traversable containing the cumulative results

size

int size()

Description copied from interface: Traversable

Returns the number of elements in this Traversable.

Alias for Traversable.length().

Specified by:

size in interface Traversable<K>

Returns:

the number of elements

toJavaMap

Map<K,V> toJavaMap()

Converts this Vavr Map to a java.util.Map while preserving characteristics like insertion order (LinkedHashMap) and sort order (SortedMap).

Returns:

a new java.util.Map instance

transform

default <U> U transform(@NonNull Function<? super Map<K,V>,? extends U> f)

Transforms this Map.

Type Parameters:

U - Type of transformation result

Parameters:

f - A transformation

Returns:

An instance of type U

Throws:

NullPointerException - if f is null

unzip

default Tuple2<Seq<K>,Seq<V>> unzip()

Unzips the entries of this Map by treating each key-value pair as an element, and splitting them into two separate Seq collections - one for keys and one for values.

Returns:

a Tuple2 containing two Seq collections: first with all keys, second with all values

unzip

default <T1,
T2> Tuple2<Seq<T1>,Seq<T2>> unzip(@NonNull BiFunction<? super K,? super V,Tuple2<? extends T1,? extends T2>> unzipper)

Unzips the entries of this Map by mapping each key-value pair to a tuple. The unzipper function transforms each entry into a Tuple2, and then all first elements are collected into the first Seq and all second elements into the second Seq.

Type Parameters:

T1 - type of the first element in the resulting pairs

T2 - type of the second element in the resulting pairs

Parameters:

unzipper - a function that maps key-value pairs of this Map to tuples

Returns:

a Tuple2 containing two Seq collections with the split elements

Throws:

NullPointerException - if unzipper is null

unzip

default <T1,
T2> Tuple2<Seq<T1>,Seq<T2>> unzip(@NonNull Function<? super Tuple2<K,V>,Tuple2<? extends T1,? extends T2>> unzipper)

Description copied from interface: Traversable

Unzips the elements of this Traversable by mapping each element to a pair and splitting them into two separate Traversable collections.

Specified by:

unzip in interface Traversable<K>

Type Parameters:

T1 - type of the first element in the resulting pairs

T2 - type of the second element in the resulting pairs

Parameters:

unzipper - a function that maps elements of this Traversable to pairs

Returns:

a Tuple2 containing two Traversable collections with the split elements

unzip3

default <T1,
T2,
T3>
Tuple3<Seq<T1>,Seq<T2>,Seq<T3>> unzip3(@NonNull BiFunction<? super K,? super V,Tuple3<? extends T1,? extends T2,? extends T3>> unzipper)

Unzips the entries of this Map by mapping each key-value pair to a triple. The unzipper function transforms each entry into a Tuple3, and then elements are distributed to respective Seq collections by their position in the tuple: all first elements into the first Seq, all second elements into the second Seq, and all third elements into the third Seq.

Type Parameters:

T1 - type of the first element in the resulting triples

T2 - type of the second element in the resulting triples

T3 - type of the third element in the resulting triples

Parameters:

unzipper - a function that maps key-value pairs of this Map to triples

Returns:

a Tuple3 containing three Seq collections with the split elements

Throws:

NullPointerException - if unzipper is null

unzip3

default <T1,
T2,
T3>
Tuple3<Seq<T1>,Seq<T2>,Seq<T3>> unzip3(@NonNull Function<? super Tuple2<K,V>,Tuple3<? extends T1,? extends T2,? extends T3>> unzipper)

Description copied from interface: Traversable

Unzips the elements of this Traversable by mapping each element to a triple and splitting them into three separate Traversable collections.

Specified by:

unzip3 in interface Traversable<K>

Type Parameters:

T1 - type of the first element in the resulting triples

T2 - type of the second element in the resulting triples

T3 - type of the third element in the resulting triples

Parameters:

unzipper - a function that maps elements of this Traversable to triples

Returns:

a Tuple3 containing three Traversable collections with the split elements

values

Seq<V> values()

Returns a new Seq that contains the values of this Map.

 // = Seq("a", "b", "c")
 HashMap.of(1, "a", 2, "b", 3, "c").values()
 

Returns:

a new Seq

valuesIterator

default Iterator<V> valuesIterator()

Returns the values in this map.

 // = Iterator.of("a", "b", "c")
 HashMap.of(1, "a", 2, "b", 3, "c").values()
 

Returns:

a new Iterator

withDefault

@Deprecated
default Function1<K,V> withDefault(@NonNull Function<? super K,? extends V> defaultFunction)

Deprecated.

Will be removed

Turns this map from a partial function into a total function that returns a value computed by defaultFunction for all keys absent from the map.

Parameters:

defaultFunction - function to evaluate for all keys not present in the map

Returns:

a total function from K to T

withDefaultValue

@Deprecated
default Function1<K,V> withDefaultValue(V defaultValue)

Deprecated.

Will be removed

Turns this map from a partial function into a total function that returns defaultValue for all keys absent from the map.

Parameters:

defaultValue - default value to return for all keys not present in the map

Returns:

a total function from K to T

zip

default <U> Seq<Tuple2<Tuple2<K,V>,U>> zip(@NonNull Iterable<? extends U> that)

Description copied from interface: Traversable

Returns a Traversable formed by pairing elements of this Traversable with elements of another Iterable. Pairing stops when either collection runs out of elements; any remaining elements in the longer collection are ignored.

The length of the resulting Traversable is the minimum of the lengths of this Traversable and that.

Specified by:

zip in interface Traversable<K>

Type Parameters:

U - the type of elements in the second half of each pair

Parameters:

that - an Iterable providing the second element of each pair

Returns:

a new Traversable containing pairs of corresponding elements

zipWith

default <U,
R> Seq<R> zipWith(@NonNull Iterable<? extends U> that,
 BiFunction<? super Tuple2<K,V>,? super U,? extends R> mapper)

Description copied from interface: Traversable

Returns a Traversable by combining elements of this Traversable with elements of another Iterable using a mapping function. Pairing stops when either collection runs out of elements.

The length of the resulting Traversable is the minimum of the lengths of this Traversable and that.

Specified by:

zipWith in interface Traversable<K>

Type Parameters:

U - the type of elements in the second parameter of the mapper

R - the type of elements in the resulting Traversable

Parameters:

that - an Iterable providing the second parameter of the mapper

mapper - a function that combines elements from this and that into a new element

Returns:

a new Traversable containing mapped elements

zipAll

default <U> Seq<Tuple2<Tuple2<K,V>,U>> zipAll(@NonNull Iterable<? extends U> that,
 Tuple2<K,V> thisElem,
 U thatElem)

Description copied from interface: Traversable

Returns a Traversable formed by pairing elements of this Traversable with elements of another Iterable, filling in placeholder elements when one collection is shorter than the other.

The length of the resulting Traversable is the maximum of the lengths of this Traversable and that.

If this Traversable is shorter than that, thisElem is used as a filler. Conversely, if that is shorter, thatElem is used.

Specified by:

zipAll in interface Traversable<K>

Type Parameters:

U - the type of elements in the second half of each pair

Parameters:

that - an Iterable providing the second element of each pair

thisElem - the element used to fill missing values if this Traversable is shorter than that

thatElem - the element used to fill missing values if that is shorter than this Traversable

Returns:

a new Traversable containing pairs of elements, including fillers as needed

zipWithIndex

default Seq<Tuple2<Tuple2<K,V>,Integer>> zipWithIndex()

Description copied from interface: Traversable

Zips this Traversable with its indices, starting at 0.

Specified by:

zipWithIndex in interface Traversable<K>

Returns:

a new Traversable containing each element paired with its index

zipWithIndex

default <U> Seq<U> zipWithIndex(@NonNull BiFunction<? super Tuple2<K,V>,? super Integer,? extends U> mapper)

Description copied from interface: Traversable

Zips this Traversable with its indices and maps the resulting pairs using the provided mapper.

Specified by:

zipWithIndex in interface Traversable<K>

Type Parameters:

U - the type of elements in the resulting Traversable

Parameters:

mapper - a function mapping an element and its index to a new element

Returns:

a new Traversable containing the mapped elements

distinct

Map<K,V> distinct()

Description copied from interface: Traversable

Returns a new Traversable containing the elements of this instance with all duplicates removed. Element equality is determined using equals.

Specified by:

distinct in interface Traversable<K>

Returns:

a new Traversable without duplicate elements

distinctBy

Map<K,V> distinctBy(@NonNull Comparator<? super Tuple2<K,V>> comparator)

Description copied from interface: Traversable

Returns a new Traversable containing the elements of this instance without duplicates, as determined by the given comparator.

Specified by:

distinctBy in interface Traversable<K>

Parameters:

comparator - a comparator used to determine equality of elements

Returns:

a new Traversable with duplicates removed

distinctBy

<U> Map<K,V> distinctBy(@NonNull Function<? super Tuple2<K,V>,? extends U> keyExtractor)

Description copied from interface: Traversable

Returns a new Traversable containing the elements of this instance without duplicates, based on keys extracted from elements using keyExtractor.

The first occurrence of each key is retained in the resulting sequence.

Specified by:

distinctBy in interface Traversable<K>

Type Parameters:

U - the type of key

Parameters:

keyExtractor - a function to extract keys for determining uniqueness

Returns:

a new Traversable with duplicates removed based on keys

drop

Map<K,V> drop(int n)

Description copied from interface: Traversable

Returns a new Traversable without the first n elements, or an empty instance if this contains fewer than n elements.

Specified by:

drop in interface Traversable<K>

Parameters:

n - the number of elements to drop

Returns:

a new instance excluding the first n elements

dropRight

Map<K,V> dropRight(int n)

Description copied from interface: Traversable

Returns a new Traversable without the last n elements, or an empty instance if this contains fewer than n elements.

Specified by:

dropRight in interface Traversable<K>

Parameters:

n - the number of elements to drop from the end

Returns:

a new instance excluding the last n elements

dropUntil

Map<K,V> dropUntil(@NonNull Predicate<? super Tuple2<K,V>> predicate)

Description copied from interface: Traversable

Returns a new Traversable starting from the first element that satisfies the given predicate, dropping all preceding elements.

Specified by:

dropUntil in interface Traversable<K>

Parameters:

predicate - a condition tested on each element

Returns:

a new instance starting from the first element matching the predicate

dropWhile

Map<K,V> dropWhile(@NonNull Predicate<? super Tuple2<K,V>> predicate)

Description copied from interface: Traversable

Returns a new Traversable starting from the first element that does not satisfy the given predicate, dropping all preceding elements.

This is equivalent to dropUntil(predicate.negate()), which is useful for method references that cannot be negated directly.

Specified by:

dropWhile in interface Traversable<K>

Parameters:

predicate - a condition tested on each element

Returns:

a new instance starting from the first element not matching the predicate

filter

Map<K,V> filter(@NonNull Predicate<? super Tuple2<K,V>> predicate)

Description copied from interface: Traversable

Returns a new traversable containing only the elements that satisfy the given predicate.

Specified by:

filter in interface Traversable<K>

Parameters:

predicate - the condition to test elements

Returns:

a traversable with elements matching the predicate

reject

Map<K,V> reject(@NonNull Predicate<? super Tuple2<K,V>> predicate)

Description copied from interface: Traversable

Returns a new traversable containing only the elements that do not satisfy the given predicate.

This is equivalent to filter(predicate.negate()).

Specified by:

reject in interface Traversable<K>

Parameters:

predicate - the condition to test elements

Returns:

a traversable with elements not matching the predicate

groupBy

<C> Map<C,? extends Map<K,V>> groupBy(@NonNull Function<? super Tuple2<K,V>,? extends C> classifier)

Description copied from interface: Traversable

Groups elements of this Traversable based on a classifier function.

Specified by:

groupBy in interface Traversable<K>

Type Parameters:

C - The type of the group keys

Parameters:

classifier - A function that assigns each element to a group

Returns:

A map where each key corresponds to a group of elements

See Also:

• Traversable.arrangeBy(Function)

grouped

Iterator<? extends Map<K,V>> grouped(int size)

Description copied from interface: Traversable

Splits this Traversable into consecutive blocks of the given size.

Let length be the number of elements in this Traversable:

• If empty, the resulting Iterator is empty.
• If size <= length, the resulting Iterator contains length / size blocks of size size and possibly a final smaller block of size length % size.
• If size > length, the resulting Iterator contains a single block of size length.

Examples:

 
 [].grouped(1) = []
 [].grouped(0) throws
 [].grouped(-1) throws
 [1,2,3,4].grouped(2) = [[1,2],[3,4]]
 [1,2,3,4,5].grouped(2) = [[1,2],[3,4],[5]]
 [1,2,3,4].grouped(5) = [[1,2,3,4]]
 
 

Note: grouped(size) is equivalent to sliding(size, size).

Specified by:

grouped in interface Traversable<K>

Parameters:

size - the block size; must be positive

Returns:

an Iterator over blocks of elements

isDefinedAt

@Deprecated
default boolean isDefinedAt(K key)

Deprecated.

Description copied from interface: PartialFunction

Tests whether a value is contained in the function's domain.

Specified by:

isDefinedAt in interface PartialFunction<K,V>

Parameters:

key - a potential input to the function

Returns:

true if the given value is contained in the function's domain, false otherwise

isDistinct

default boolean isDistinct()

Description copied from interface: Traversable

Indicates whether this Traversable may contain only distinct elements.

Specified by:

isDistinct in interface Traversable<K>

Returns:

true if this Traversable may contain only distinct elements, false otherwise

init

Map<K,V> init()

Description copied from interface: Traversable

Returns all elements of this Traversable except the last one.

This is the dual of Traversable.tail().

Specified by:

init in interface Traversable<K>

Returns:

a new instance containing all elements except the last

initOption

Option<? extends Map<K,V>> initOption()

Description copied from interface: Traversable

Returns all elements of this Traversable except the last one, wrapped in an Option.

This is the dual of Traversable.tailOption().

Specified by:

initOption in interface Traversable<K>

Returns:

Some(traversable) if non-empty, or None if this Traversable is empty

orElse

Map<K,V> orElse(Iterable<? extends Tuple2<K,V>> other)

Description copied from interface: Traversable

Returns this Traversable if it is non-empty; otherwise, returns the given alternative.

Specified by:

orElse in interface Traversable<K>

Parameters:

other - an alternative Traversable to return if this is empty

Returns:

this Traversable if non-empty, otherwise other

orElse

Map<K,V> orElse(@NonNull Supplier<? extends Iterable<? extends Tuple2<K,V>>> supplier)

Description copied from interface: Traversable

Returns this Traversable if it is non-empty; otherwise, returns the result of evaluating the given supplier.

Specified by:

orElse in interface Traversable<K>

Parameters:

supplier - a supplier of an alternative Traversable if this is empty

Returns:

this Traversable if non-empty, otherwise the result of supplier.get()

partition

Tuple2<? extends Map<K,V>,? extends Map<K,V>> partition(@NonNull Predicate<? super Tuple2<K,V>> predicate)

Description copied from interface: Traversable

Splits this Traversable into two partitions according to a predicate.

The first partition contains all elements that satisfy the predicate, and the second contains all elements that do not. The original iteration order is preserved.

Specified by:

partition in interface Traversable<K>

Parameters:

predicate - a predicate used to classify elements

Returns:

a Tuple2 containing the two resulting Traversable instances

peek

Map<K,V> peek(@NonNull Consumer<? super Tuple2<K,V>> action)

Description copied from interface: Value

Performs the given action on the first element if this is an eager implementation. Performs the given action on all elements (the first immediately, successive deferred), if this is a lazy implementation.

Specified by:

peek in interface Traversable<K>

Specified by:

peek in interface Value<K>

Parameters:

action - The action that will be performed on the element(s).

Returns:

this instance

replace

Map<K,V> replace(@NonNull Tuple2<K,V> currentElement,
 @NonNull Tuple2<K,V> newElement)

Description copied from interface: Traversable

Replaces the first occurrence of currentElement with newElement, if it exists.

Specified by:

replace in interface Traversable<K>

Parameters:

currentElement - the element to be replaced

newElement - the replacement element

Returns:

a new Traversable with the first occurrence of currentElement replaced by newElement

replaceValue

Map<K,V> replaceValue(K key,
 V value)

Replaces the entry for the specified key only if it is currently mapped to some value.

Parameters:

key - the key of the element to be substituted.

value - the new value to be associated with the key

Returns:

a new map containing key mapped to value if key was contained before. The old map otherwise.

replace

Map<K,V> replace(K key,
 V oldValue,
 V newValue)

Replaces the entry for the specified key only if currently mapped to the specified value.

Parameters:

key - the key of the element to be substituted.

oldValue - the expected current value that the key is currently mapped to

newValue - the new value to be associated with the key

Returns:

a new map containing key mapped to newValue if key was contained before and oldValue matched. The old map otherwise.

replaceAll

Map<K,V> replaceAll(@NonNull BiFunction<? super K,? super V,? extends V> function)

Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception.

Parameters:

function - function transforming key and current value to a new value

Returns:

a new map with the same keySet but transformed values.

replaceAll

Map<K,V> replaceAll(@NonNull Tuple2<K,V> currentElement,
 Tuple2<K,V> newElement)

Description copied from interface: Traversable

Replaces all occurrences of currentElement with newElement.

Specified by:

replaceAll in interface Traversable<K>

Parameters:

currentElement - the element to be replaced

newElement - the replacement element

Returns:

a new Traversable with all occurrences of currentElement replaced by newElement

retainAll

Map<K,V> retainAll(@NonNull Iterable<? extends Tuple2<K,V>> elements)

Description copied from interface: Traversable

Retains only the elements from this Traversable that are contained in the given elements.

Specified by:

retainAll in interface Traversable<K>

Parameters:

elements - the elements to keep

Returns:

a new Traversable containing only the elements present in elements, in their original order

scan

Map<K,V> scan(@NonNull Tuple2<K,V> zero,
 @NonNull BiFunction<? super Tuple2<K,V>,? super Tuple2<K,V>,? extends Tuple2<K,V>> operation)

Description copied from interface: Traversable

Computes a prefix scan of the elements of this Traversable.

The neutral element zero may be applied more than once.

Specified by:

scan in interface Traversable<K>

Parameters:

zero - the neutral element for the operator

operation - an associative binary operator

Returns:

a new Traversable containing the prefix scan of the elements

slideBy

Iterator<? extends Map<K,V>> slideBy(@NonNull Function<? super Tuple2<K,V>,?> classifier)

Description copied from interface: Traversable

Partitions this Traversable into consecutive non-overlapping windows according to a classification function.

Each window contains elements with the same class, as determined by classifier. Two consecutive elements belong to the same window only if classifier returns equal values for both. Otherwise, the current window ends and a new window begins with the next element.

Examples:

 [].slideBy(Function.identity()) = []
 [1,2,3,4,4,5].slideBy(Function.identity()) = [[1],[2],[3],[4,4],[5]]
 [1,2,3,10,12,5,7,20,29].slideBy(x -> x / 10) = [[1,2,3],[10,12],[5,7],[20,29]]
 

Specified by:

slideBy in interface Traversable<K>

Parameters:

classifier - A function classifying elements into groups

Returns:

An Iterator of windows (grouped elements)

sliding

Iterator<? extends Map<K,V>> sliding(int size)

Description copied from interface: Traversable

Slides a window of a given size over this Traversable with a step size of 1.

This is equivalent to calling Traversable.sliding(int, int) with a step size of 1.

Specified by:

sliding in interface Traversable<K>

Parameters:

size - a positive window size

Returns:

An Iterator of windows, each containing up to size elements

sliding

Iterator<? extends Map<K,V>> sliding(int size,
 int step)

Description copied from interface: Traversable

Slides a window of a specific size with a given step over this Traversable.

Examples:

 [].sliding(1, 1) = []
 [1,2,3,4,5].sliding(2, 3) = [[1,2],[4,5]]
 [1,2,3,4,5].sliding(2, 4) = [[1,2],[5]]
 [1,2,3,4,5].sliding(2, 5) = [[1,2]]
 [1,2,3,4].sliding(5, 3) = [[1,2,3,4],[4]]
 

Specified by:

sliding in interface Traversable<K>

Parameters:

size - a positive window size

step - a positive step size

Returns:

an Iterator of windows with the given size and step

span

Tuple2<? extends Map<K,V>,? extends Map<K,V>> span(@NonNull Predicate<? super Tuple2<K,V>> predicate)

Description copied from interface: Traversable

Splits this Traversable into a prefix and remainder according to the given predicate.

The first element of the returned Tuple is the longest prefix of elements satisfying predicate, and the second element is the remaining elements.

Specified by:

span in interface Traversable<K>

Parameters:

predicate - a predicate used to determine the prefix

Returns:

a Tuple containing the prefix and remainder

tail

Map<K,V> tail()

Description copied from interface: Traversable

Returns a new Traversable without its first element.

Specified by:

tail in interface Traversable<K>

Returns:

a new Traversable containing all elements except the first

tailOption

Option<? extends Map<K,V>> tailOption()

Description copied from interface: Traversable

Returns a new Traversable without its first element as an Option.

Specified by:

tailOption in interface Traversable<K>

Returns:

Some(traversable) if non-empty, otherwise None

take

Map<K,V> take(int n)

Description copied from interface: Traversable

Returns the first n elements of this Traversable, or all elements if n exceeds the length.

Equivalent to sublist(0, max(0, min(length(), n))), but safe for n < 0 or n > length().

If n < 0, an empty instance is returned. If n > length(), the full instance is returned.

Specified by:

take in interface Traversable<K>

Parameters:

n - the number of elements to take

Returns:

a new Traversable containing the first n elements

takeRight

Map<K,V> takeRight(int n)

Description copied from interface: Traversable

Returns the last n elements of this Traversable, or all elements if n exceeds the length.

Equivalent to sublist(max(0, length() - n), length()), but safe for n < 0 or n > length().

If n < 0, an empty instance is returned. If n > length(), the full instance is returned.

Specified by:

takeRight in interface Traversable<K>

Parameters:

n - the number of elements to take from the end

Returns:

a new Traversable containing the last n elements

takeUntil

Map<K,V> takeUntil(@NonNull Predicate<? super Tuple2<K,V>> predicate)

Description copied from interface: Traversable

Takes elements from this Traversable until the given predicate holds for an element.

Equivalent to takeWhile(predicate.negate()), but useful when using method references that cannot be negated directly.

Specified by:

takeUntil in interface Traversable<K>

Parameters:

predicate - a condition tested sequentially on the elements

Returns:

a new Traversable containing all elements before the first one that satisfies the predicate

takeWhile

Map<K,V> takeWhile(@NonNull Predicate<? super Tuple2<K,V>> predicate)

Description copied from interface: Traversable

Takes elements from this Traversable while the given predicate holds.

Specified by:

takeWhile in interface Traversable<K>

Parameters:

predicate - a condition tested sequentially on the elements

Returns:

a new Traversable containing all elements up to (but not including) the first one that does not satisfy the predicate